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Oecologia

, Volume 154, Issue 2, pp 387–402 | Cite as

Untangling the roles of fire, grazing and rainfall on small mammal communities in grassland ecosystems

  • R. W. Yarnell
  • D. M. Scott
  • C. T. Chimimba
  • D. J. Metcalfe
Community Ecology

Abstract

In grassland systems across the globe, ecologists have been attempting to understand the complex role of fire, grazing and rainfall in creating habitat heterogeneity and the consequences of anthropogenic control of these factors on ecosystem integrity and functioning. Using a South African grassland ecosystem as a model, we investigated the impact of fire and grazing pressure on small mammal communities during three differing periods of a rainfall cycle. Over 2 years, 15,203 trap nights revealed 1598 captures of 11 species (nine rodents, one macroscelid and one insectivore). Results highlighted the importance of the interplay between factors and showed that the role of fire, grazing and rainfall in determining small mammal abundance was species-dependant. While no two species were affected by the same environmental variables, grass cover or height was important to 56% of species. Considered independently, high rainfall had a positive influence on small mammal abundance and diversity, although the lag period in population response was species-specific. High grazing negatively affected overall abundance, but specifically in Mastomys coucha; fire alone had little immediate impact on small mammal diversity. Six months after the fire, vegetation cover had recovered to similar levels as unburned areas, although small mammal diversity and richness were higher in burned areas than unburned areas. Grazing levels influenced the rate of vegetation recovery. In conclusion, low-level grazing and burning can help to maintain small mammal biodiversity, if conducted under appropriate rainfall levels. A too high grazing pressure, combined with fire, and/or fire conducted under drought conditions can have a negative impact on small mammal biodiversity. To maintain small mammal diversity in grassland ecosystems, the combined effects of the previous year’s rainfall and existing population level as well as the inhibition of vegetation recovery via grazing pressure need to be taken into consideration before fire management is applied.

Keywords

Diversity Management Rodents Savanna 

Notes

Acknowledgements

Research was funded by a University of Brighton Studentship and a British Airways RGS travel bursary. We are especially gratefully to Dougal McTavish and Lynne McTavish for site access and support during fieldwork. We are also grateful to Steve Waite and Liz Cheek for comments on statistical procedures. Thanks to the staff at the Mammal Research Institute, University of Pretoria, South Africa for their support and guidance, especially to Dr. Amanda Bastos for DNA sequencing. All capture, handling and sampling methods were approved by the Animal Ethics Committee of the University of Pretoria. Caroline Bruce, Adam McKeown and two anonymous referees greatly improved earlier drafts of this paper.

Supplementary material

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • R. W. Yarnell
    • 1
  • D. M. Scott
    • 1
  • C. T. Chimimba
    • 2
  • D. J. Metcalfe
    • 3
  1. 1.Department of Biological SciencesUniversity of BrightonBrightonUK
  2. 2.DST-NRF Centre of Excellence for Invasion Biology (CIB), Department of Zoology and EntomologyUniversity of PretoriaPretoriaSouth Africa
  3. 3.CSIRO Sustainable EcosystemsTropical Forest Research CentreAthertonAustralia

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